Pointer inconsistencies in 2L

The 2L spec defines the pointer operations as follows:

          | Up: Move the data pointer to the right (> in BF)
          | Down: Move the data pointer to the left (< in BF)

In Gregor Richards's 2L interpreter, these operations are actually reversed;
a * encountered going down moves the data pointer to the right, and a *
encountered going up moves the data pointer to the left.

HelloWorld.2l was tested with this interpreter and therefore assumes this
incorrect (or at least contrary to the documentation) behavior.
